Decentralized systems, such as distributed ledgers and the InterPlanetary File System (IPFS), are designed to offer more open and robust services. However, they also create opportunities for illegal activities. We demonstrate how these technologies can be used to launch a ransomware as a service campaign. We show that criminals can transact with affiliates and victims without having to reveal their identity. Furthermore, by exploiting the robustness and resilience to churn of IPFS, as well as the decentralized computing capabilities of Ethereum, criminals can remain offline during most procedures, with many privacy guarantees.

We explore the adoption of the Internet of Things (IoT) and Distributed Ledger Technologies (DLTs), such as blockchains, in mobile gaming, focusing on ecosystem expansion and diversification, customer attraction and retention, exploitation of context sensitive and personalized advertisements, and improved monetization of in-game assets. We evaluate the cost and transaction delay of DLTs in a location-based mobile game ecosystem using two types of blockchains (permissioned and permissionless or public), based on defined Key Performance Indicators (KPIs). Our evaluation shows the advantages of using both types of blockchains as well as interledger technologies that combine them. Permissioned blockchains enable high performance, e.g., in terms of throughput and delay, and low cost, while permissionless (public) blockchains, through their transparency, immutability, and openness, support trust and facilitate interactions among unrelated parties. Finally, we show that the combination of IoT devices and DLTs in mobile gaming offers new business opportunities and enables innovative business models for both traditional mobile gaming companies and other participants in the ecosystem, e.g., game players, cafes, malls, and similar establishments, advertising companies, and independent programmers.

The proliferation of Internet of Things (IoT) devices that operate unattended providing a multitude of important and often sensitive services highlights the need for seamless interoperability and increased security. We argue that digital twins of IoT devices, with the right design, can enhance the security, reliability, auditability, and interoperability of IoT systems. The salient features of digital twins have made them key elements for the IoT and Industry 4.0. In this paper, we leverage advances in W3C's Web of Things (WoT) standards and Distributed Ledger Technologies (DLTs) to present a novel design of smart contract-based digital twins with enhanced security, transparency, interoperabilty, and reliability. We provide two different variations of that general design using two different blockchains (one public and one private, permissioned blockchain), and we present design trade-offs. Furthermore, we introduce an architecture for accessing and controlling IoT devices securely, reliably, providing full auditability, while at the same time using the proposed digital twins as an indirection mechanism (proxy). The proposed architecture leverages the blockchain to offer notable properties, namely, decentralization, immutability, auditability, non-repudiation, availability, and reliability. Moreover, it introduces mass actuation, easier management of IoT devices, enhanced security to the IoT gateways, it enables new business models, and it makes consumer devices (vendor-)agnostic.